Effects of novel organic sources of cobalt on ruminal fermentation, nutrient degradation and vitamin B12 synthesis in vitro

Lay Summary Effects of novel organic sources of cobalt on ruminal fermentation, nutrient degradation and vitamin B12 synthesis in vitro. By Arce-Cordero et al., page XX. Cobalt (Co) is required for ruminal synthesis of vitamin B12 which is essential for propionate and energy metabolism of the host animal. Reports of the effects of organic Co sources on cow performance are variable and primarily focused on Co glucoheptonate. We evaluated the effects of Co amino acid (CoAA), Co pectin, and a combination of both as novel sources of organic Co on in vitro ruminal fermentation compared to CoCO3. We hypothesized that the greater solubility of organic Co sources would enable greater Co utilization by ruminal microorganisms, and therefore greater synthesis of vitamin B12 and propionate compared to CoCO3. We did not find an effect of Co source on propionate, however our results suggest greater utilization of Co when CoAA is included as the main supplemental source of Co in dairy cattle diets, as indicated by lower lactate, greater microbial synthesis of protein and N use efficiency, and greater outflow of vitamin B12, compared to CoCO3.